Nook balancing a automobile has been a type of issues that appeared off-limits to the typical automotive DIY fanatic.
You will discover a variety of digital scales from a velocity store like Summit Racing; nevertheless, a ‘first rate’ set will set you again at the very least $1,000, and a higher-quality set will price double that.
You should use the toilet scale hack, the place you jack the automobile up and decrease it on a set of low-cost toilet scales. I even tried this again in 2020 with Challenge Tough, my ER34 Nissan Skyline GT-T, and had… reasonable success.
To do that accurately, it’s essential to guarantee you might be engaged on a wonderfully flat floor. The automobile must be as degree as potential whereas on the scales – i.e., on some type of platform – and also you want a method to loosen up the arms after jacking the automobile as much as transfer the scales into place.
It’s fairly the dance, and there are a bunch of variables the place issues can go improper. Considered one of my scales broke attributable to going far past the utmost weight restrict of 130kg (286lbs).
So, measuring the load in any respect 4 corners, making any changes, and having to carry out the entire circus once more made this method removed from sensible. It appeared like devoted digital scales have been nonetheless the one viable strategy.
Or Is It…
Quick-forward just a few years, and I found a YouTube channel referred to as SuperfastMatt. Matt’s movies are as humorous as they’re insightful, and one referred to as I Invented a Higher Method to Weigh Your Automotive. And it’s Cheaper, Too. discusses how you should utilize leverage and a little bit of math to calculate the load at any given nook.
You could have a supporting block wherein a beam rests on. The supporting block is a ‘X’ distances away from the toilet scale. You’d then place the tire on the beam, and that weight transfers throughout the beam to the dimensions. The burden shall be considerably smaller, which shouldn’t max out the dimensions. If you understand the space from the supporting block and the space to the dimensions, you possibly can calculate the precise weight with the worth proven by the dimensions.
Seeing that I nonetheless had my analog scales from the primary try and a workable platform I designed for aligning vehicles, I figured I’d let my inside engineer again out to play and provides this a shot. Earlier than going full ship, I made a decision to check it on a small scale with an previous battery from the household Honda Stepwgn.
I first weighed the battery to know my goal— roughly 9.8kg (21.6lbs). The decision on these scales go away lots to want.
I subsequent created a platform that may have the beam degree with the toilet scale. I recorded the size (92.2cm). We are going to name this ‘L’.
Then I positioned the battery on the beam and acquired a studying of two.9kg (6.4lbs). Nice! I’ll name that ‘Fa’ for now. Now, to calculate the distances.
Not like the drawing, the drive of the battery isn’t a single level on the beam, thus I made a decision to take the typical of utilizing a distance from in entrance of and behind the battery – one closest to the dimensions (L2) and one closest to the supporting block (L1). I might subtract the 2 and divide it by 2.
(L2-L1) /2 = Lm
(39cm-15.5cm) / 2 = Lm
11.75cm = Lm
With what I’m calling ‘Lm’, you possibly can subtract that quantity from L2 and get the battery’s ‘heart’ level of drive. I’ll name this worth ‘Lf’.
L2-Lm= Lf
39cm-11.75cm= Lf
27.25cm= Lf
With Lf now decided, I can divide it by the entire size of the beam. If you understand the space relative to the beam, you possibly can divide that quantity by the load on the dimensions to calculate the load. I do know it’s getting a bit wild right here…
Fl=Lf /L
Fl=27.25cm / 92.2cm
Fl=.2955
I discovered this on the full-size check, however I attempted to maintain as many numbers after the decimal place as potential to extend accuracy. It does make a distinction. With Fl, we are able to lastly calculate the load of F.
F= Fa / Fl
F= 2.9kg. / 2955
F= 9.81kg
That is an error of 0.10%, which greater than proves the accuracy of this mathematical check. With this stable proof of idea, it was time to scale up.
Full Steam Forward
With Challenge Tough able to go, I made a decision to do an alignment, as I might use the identical platform rig for the nook balancing.
For shaken, I needed to reinstall some OEM components, which threw my alignment out of whack.
Bringing the automobile to my home from its storage spot was one of many sketchiest drives of my life. I adjusted my laser degree to degree the platform with shims.
I used to be now able to nook steadiness Challenge Tough. I acquired my toilet scale out and ensured the beam and platform have been degree…
…And instantly bumped into an issue. Though I had calculated that if my bar have been 184cm lengthy, I might have loads of house to drive on the beam and never max out the toilet scale, the load deflected the beam a lot that it touched the bottom. Two extrusion bars weren’t going to work.
However how about three? Seeing that I had additional extrusions from numerous tasks at that very same 184cm size, I made a decision to attempt that earlier than chopping the beams to a smaller measurement. I used to be nonetheless afraid that if I had minimize the beams too brief and pushed too far on the beam, it might max out the dimensions, and I’d threat breaking them.
Even with three beams in place, they nonetheless bowed like loopy. This wasn’t going to work. I then remembered that I may transfer the dimensions nearer to the automobile and use a wedge piece of wooden for the beams to relaxation on to switch the load, successfully shorting the size of the beams. All I wanted to do was zero out my scale and check out it.
With my present size (L) now shortened to 108.3cm from 184cm, the beam hardly deflected and will proceed with the experiment. The studying on the dimensions was 42.5kg (93.7lbs) (Fa).
It was now time to calculate the varied lengths as I had completed with the battery. Nonetheless, it was tougher to inform the place the contact patch was on the beam. I used a small sq. ruler and slid it underneath the tire till it couldn’t transfer anymore, after which marked the beam. I did this for each side to get my L2 and L1 calculations.
(L2-L1) / 2 = Lm
(20.5cm-1.1cm) / 2 = Lm
9.7cm = Lm
It wasn’t till I completed measuring all the things that I noticed there was a neater method to decide the tire’s contact patch…
You possibly can press a chunk of flat scrap wooden anyplace in opposition to the tire and mark out the L2 and L1 of the tire contact patch utilizing the identical technique. Amazingly, this technique matched my numbers for the entrance tires (9.7cm) however was barely increased within the rear (10cm). These can be the Lm values used within the calculations.
Seeing that I can instantly calculate Lm from the tire contact patch, my new equation is now this.
L2-Lm = Lf
20.5cm -9.7cm = Lf
Lf = 10.8cm
We now take Lf and calculate the drive relative to the space on the beam.
Fl=Lf / L
Fl=10.8cm / 108.3cm
Fl=.0997
Once more, maintain as many locations as potential within the calculations. I saved the whole quantity on my calculator (0.099722992). Then, we are able to calculate the drive of the automobile at that nook.
F= Fa / Fl
F= 42.5kg.0997
F= 426.18kg
And similar to that, one nook is completed! Subsequent, roll the automobile again a bit, transfer the dimensions to the following tire, drive up, and crunch these numbers.
When you get the cling of it, every nook takes about 5 minutes. In fact, you probably have a number of scales and beams (I used to be nonetheless cautious and determined to not get extra beams to do that), you may do that complete course of in a single shot.
Listed here are the values that I got here up with after all of the calculations. In response to the shakensho, my Skyline ought to weigh 1,460kg (3,218lbs). I’m unsure how they acquired that quantity (moist, dry, full tank of gasoline, and so forth.), however I shouldn’t be too far off.
Think about an excellent light-weight (learn: barely flimsy) FRP entrance hood, no spare tire, and some different bits right here and there, and the entire calculated weight is fairly rattling shut. Ideally, I might take Challenge Tough to a spot the place I can drive and weigh the automobile, however that should wait till it’s handed its shaken inspection.
What can we do with this newfound details about Challenge Tough‘s steadiness? A nook steadiness reveals your automobile’s weight distribution, which may then be manipulated to optimize dealing with. For many who are lifeless severe about getting the perfect lap time, you’d manipulate this distribution by bodily eradicating weight or including ballast in strategic places to get nearer to that ‘ideally suited’ 50/50 distribution entrance to again and left to proper.
We will manipulate how a lot weight a nook receives by elevating or decreasing it. Nonetheless, as one motion impacts all the opposite corners on the identical time, it isn’t potential to alter the entrance, rear, left, and proper weight percentages. So except I bodily take away, shift, or add weight, Challenge Tough can have these values.
Entrance Weight % =54.06%
Rear Weight % =45.95%
Left Weight % =53.23%
Proper Weight % =46.77%
Be aware: I didn’t simulate my physique weight (84kg/185lbs) or disconnect the sway bars. In good observe, you completely ought to do that when organising a race automobile or a automobile with extremely stiff springs. Minor tweaks can have a much bigger impact, and also you don’t need unintended preload within the sway bars. Though Challenge Tough has adjustable sway bar finish hyperlinks, and I’ve dialed them in for no preload, it isn’t a race automobile. We’re nonetheless doing this with toilet scales no matter what number of variables we restrict.
What we can do is get our cross-weight to a great 50/50 scenario. At the moment:
(Entrance Proper (kg) +Rear Left (kg)) / Whole Weight (kg) = Cross Weight %
(351.83kg+340kg) / 1439.27kg =Cross Weight %
48.07% = Cross Weight %
Anytime you could have a cross weight above 50%, you could have a wedge. Something under 50%, like Challenge Tough, is a reverse wedge. Understanding this, you possibly can observe these guidelines to regulate the experience peak to get nearer to a 50/50 distribution.
RAISING anybody nook will INCREASE the load on that nook and barely have an effect on all different corners.
LOWERING anybody nook will DECREASE the load on that nook and barely have an effect on all different corners.
Cross weight ABOVE 50% = DECREASE weight (peak) on FR/RL or INCREASE weight (peak) on FL/RR. – Wedge
Cross weight BELOW 50% = INCREASE weight (peak) on FR/RL or DECREASE weight (peak) on FL/RR – Reverse Wedge
Thus, I ought to work on growing the peak on the Entrance Proper – Rear Left or reducing the peak on the Entrance Left – Rear Proper. That is the place all the things turns into hella-tedious. You additionally must determine how set you might be within the automobile’s experience peak. Once more, the stiffer the springs, the stronger the impression minor changes will make. Nonetheless, if you’re lifeless set on how the automobile seems, you may need to compromise that fifty/50 distribution.
And that’s so that you can determine. For me, as soon as I get Challenge Tough again on the highway, I’ll do that once more and goal to get that fifty/50 cross weight distribution. I additionally wish to check just a few extra suspension tasks and experiments.
This goes to point out that should you’re not afraid of a bit little bit of math, you possibly can unlock potential and knowledge that may in any other case be locked behind costly gear. It did take some refinement, and this nonetheless received’t be as correct as an excellent set of digital scales, however not like my first try at nook balancing with scales, it was successful.
Digital scales would nonetheless be glorious, although…
Ron Celestine
Instagram: celestinephotography
